# PT-141 (Bremelanotide): What the Research and the FDA Label Establish > PT-141 (bremelanotide) is an FDA-approved melanocortin receptor agonist for HSDD in premenopausal women. A cited, calm digest of the mechanism, the trials, and the regulatory scope. A calm, cited reading of the trials and the label: one approved use, a real but modest effect, and an honest tolerability picture — with everything off-label marked as off-label. ## The short version PT-141 is the research name for bremelanotide, a lab-made copy of a natural body signal (the hormone alpha-MSH) that flips brain switches involved in sexual desire. The U.S. FDA approved it in June 2019, but for exactly one thing: acquired, generalized HSDD (hypoactive sexual desire disorder — persistent low sexual desire that causes real personal distress) in premenopausal women, given as a small injection just under the skin [3][6]. It works in the brain, not by changing blood flow the way erection pills do. Every other use — in men, for erectile problems, in postmenopausal women — is off-label and still being studied. This page summarizes that published record; it sells nothing and recommends no dose. ## PT-141 peptide: a synthetic melanocortin agonist PT-141 is a synthetic cyclic heptapeptide — a ring of seven amino acids — built as an analogue of alpha-MSH (alpha-melanocyte-stimulating hormone), an endogenous signaling peptide the body cleaves from a larger precursor protein called POMC [1]. Its full sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, with a lactam bridge (a stabilizing chemical clasp) tying two side chains into a ring; that ring makes it sturdier than the linear melanocortin peptides it descends from. It is a close structural relative of melanotan II, with the C-terminal end changed from an amide to a carboxylic acid. The molecule weighs roughly 1025 Da, carries CAS number 189691-06-3, and is catalogued under the INN "bremelanotide." Sold as a finished pharmaceutical it is a regulated drug; sold as a "research chemical" it is laboratory material outside that approval. ## What a melanocortin receptor agonist is A melanocortin receptor agonist is a molecule that switches on the melanocortin receptors — a family of five G-protein-coupled receptors (MC1R through MC5R) that normally respond to alpha-MSH and related peptides. PT-141 chiefly activates the central subtypes MC4R and, secondarily, MC3R [1]. These sit in the brain, concentrated in the hypothalamus and limbic system, where they help regulate sexual motivation and appetite. This is the key distinction from PDE-5 inhibitors (the class that includes sildenafil and tadalafil): those act peripherally on vascular smooth muscle to improve erectile blood flow, while a melanocortin agonist acts centrally on the neural circuitry of desire itself. Activation of the peripheral MC1R subtype is the reason repeated dosing can darken skin and gums — a point the [PT-141 side effects](/side-effects) page returns to. ## PT-141 for women: the approved HSDD indication The single FDA-approved use for PT-141 (bremelanotide) is acquired, generalized HSDD in premenopausal women [3][6]. That approval rests on two identical Phase 3 randomized controlled trials — the RECONNECT program — which together enrolled 1,267 premenopausal women with HSDD. Over 24 weeks, bremelanotide 1.75 mg given subcutaneously (injected just under the skin) on an as-needed basis met both coprimary endpoints: it improved sexual desire (integrated FSFI-desire score +0.35 versus placebo, P<.001) and reduced the distress that low desire caused (integrated FSDS-DAO item-13 score −0.33, P<.001) [3]. FSFI and FSDS are the standard validated questionnaires trials use to score sexual desire and the distress low desire causes. The effect is statistically real and was sustained in a 52-week extension [4] — and, as the [PT-141 in the research literature](/research) section details, it is also clinically modest, a characterization independent re-analysts have pressed [12]. ## How PT-141 works, in the brain PT-141 acts on the brain, not on blood vessels. By stimulating MC4R in hypothalamic circuits — notably the medial preoptic area (mPOA), a region central to sexual motivation — it is thought to engage dopaminergic signaling pathways that govern appetitive, desire-driven sexual behavior [1]. The preclinical record is consistent with that central mechanism: in rats and nonhuman primates, systemic PT-141 produced erections and lit up hypothalamic neurons (measured as increased c-Fos), and in female rats it selectively increased solicitational, desire-type behaviors without changing reflexive ones [1][2]. A 2022 placebo-controlled fMRI study in 31 women with HSDD added direct human mechanistic evidence: MC4R agonism increased sexual desire for up to 24 hours and altered how the brain processed erotic stimuli, enhancing amygdala-insula connectivity [5]. Curiosity about the mechanism continues — a 2025 hamster study found the drug did not act on the brain's reward circuit, a nuanced negative finding [13]. ### PT-141 mechanism of action PT-141's mechanism of action is central MC4R (and secondary MC3R) agonism in hypothalamic and limbic circuits linked to sexual desire [1]. By activating MC4R in regions such as the medial preoptic area, it is thought to recruit dopaminergic pathways that drive sexual motivation [5]. It does not work through blood flow and does not act on the HPG (reproductive-hormone) axis. ### Is PT-141 the same as bremelanotide? Yes. PT-141 is the research designation for bremelanotide, the international nonproprietary name (INN) of this melanocortin receptor agonist [6]. The two names refer to the same molecule; "PT-141" is the development code, "bremelanotide" the official drug name carried on the FDA-approved injection. ## Is PT-141 FDA-approved, and is it legal? PT-141 (bremelanotide) is FDA-approved, but its approval is narrow — and that scope is the most important fact on this site. ### Is PT-141 FDA-approved? Yes, but only for one indication. Bremelanotide injection was approved on June 21, 2019 (NDA 210557) solely for acquired, generalized HSDD in premenopausal women [3][6]. Use in men, in postmenopausal women, for erectile dysfunction, or for sexual "performance" is off-label and not covered by that approval. Material sold as "PT-141 research chemical" sits outside the approved finished-drug product, with no regulatory oversight of its identity, purity, or concentration. ### Is PT-141 legal in the US? Bremelanotide is an FDA-approved prescription drug for HSDD in premenopausal women; it is not a U.S. controlled or scheduled substance [6]. The "PT-141" research-chemical form is laboratory material only and is not the approved finished drug. For competitive athletes, melanocortin agonists fall under WADA's non-approved-substances framework (S0); anyone affected should consult current WADA guidance directly. ### What is PT-141? PT-141 is the research designation for bremelanotide, a synthetic cyclic heptapeptide analogue of the hormone alpha-MSH that activates central melanocortin MC3R/MC4R receptors [1]. Its [approval and regulatory status](/) defines what it is cleared to treat. ### What is bremelanotide? Bremelanotide is a synthetic cyclic heptapeptide melanocortin (MC3R/MC4R) agonist; the FDA approved it in June 2019 as a subcutaneous injection for acquired, generalized HSDD in premenopausal women [3][6]. ### What is PT-141 used for? Its single FDA-approved use is acquired, generalized HSDD in premenopausal women [3]. It has also been studied off-label and investigationally for male erectile dysfunction [11] and was examined in early female-arousal and metabolic research [7]. --- A calm clinical-platform reading of the bremelanotide record, read in low light — the approved-for-premenopausal-HSDD-only scope surfaced first, the cited trial and label evidence flagged green, the unverified field reports fenced off amber; no clinic behind the platform and nothing here prescribed, dispensed, or sold.